The overall goal of this study is to ascertain whether the treatment with SR-NaF would correct the underlying disturbance and be clinically useful in idiopathic osteoporosis, by conducting a placebo-controlled randomized trial. The goal of this trial is to validate findings from a non-randomized trial that SR-NaF treatment is clinically effective and safe in this condition. A secondary goal is to ascertain whether the defective bone formation in idiopathic osteoporosis might be due to impaired osteoblastic synthesis of growth factors, and if the treatment with SR-NaF might correct the disturbance in osteoblastic function. From bone biopsies procured from selected patient taking eith SR-NaF or placebo, cancellous bone will be examined for the synthesis of growth factors.